Petshrimp.com Discussion Forum

These things scare me.

Because they reproduce asexually, they have incredible potential as an invasive species. Just one getting loose and into a local waterway could spell disaster for native crayfish species.

The best prevention is to be informed, thanks all.

They are a great looking cray

I'm surprised they haven't been restricted already, considering the potential problems if/when one gets loose somewhere. On the other hand, if they don't find a suitable natural environment, their potential is limited in the long run. A species that essentially clones a single individual is at an evolutionary dead-end.

A species that essentially clones a single individual is at an evolutionary dead-end.

Is this due to their inability to genetically evolve/adapt as generations go on?

YuccaPatrol wrote:These things scare me.

Because they reproduce asexually, they have incredible potential as an invasive species. Just one getting loose and into a local waterway could spell disaster for native crayfish species.

Of course nobody should just throw any exotic animal in local waterways, but I think the potential of this species to be invasive is rather limited. They are relatively small, all female (and hence very small claws) and do not display aggressive behavior like most crayfish their size or larger. With those small claws and docile behavior they would not stand a chance competing with pretty much all native species (most of which are very, very aggressive). And a crayfish that can't find a hiding space under a rock during the day quickly becomes fish food.

ToddnBecka wrote:A species that essentially clones a single individual is at an evolutionary dead-end.

This isn't nessesarily so. We are just now starting to find there is more to evolution than just mutation. Existing genes have environmental switches and these can caause the animal to adapt even without new mutations.

Is this the cray they are having problems with in the UK/EU?

Thanks,

TKD

badflash wrote:

ToddnBecka wrote:A species that essentially clones a single individual is at an evolutionary dead-end.

This isn't nessesarily so. We are just now starting to find there is more to evolution than just mutation. Existing genes have environmental switches and these can caause the animal to adapt even without new mutations.

Plus, genes can mutate "all of a sudden", too (e.g. through UV rays, radioactivity, chemicals..etc..etc.). The clone offspring would then carry these mutated genes and would be different from all the other clones who are not offspring of the mutated animal.

I think this won't be a problem for the hobbiest. I see no way these would have an economic impact. Unless they do, the government won't do anything about it. It takes money to do enforcement or intervention.

TKD the problem crayfish in the UK is the signal crayfish, not the marmorkrebs.

I think the marmorkrebs could have a problem establishing themselves in the wild because of their passive nature, but if they were to get established they could devastate the ecological balance of an area. Since they are thought to have originated in Florida, I don't believe they could survive the northern winters. Perhaps a study needs to be done to see how much cold they can handle and survive.

The quickest way to find out would be to put one outside in a bucket overnight while the temps are still cold. Obviously, you wouldn't want to allow it to freeze, but as long as the water didn't do more than ice over at the surface, it would be a good indication of their cold tolerance regarding invasive potential.

A study has been done and they can overwinter in northern climates. I can share a paper with youif you PM me with an E-Mail. I think they would be challenged by the local residents and eaten alive.

Badflash, after watching the babies in my tank I think you are correct about them losing out to the native inhabitants. The babies never hide and hardly move when I put my hand in to shoo them away from the filter intake so I can change the prefilter. I really don't think they would do well in the wild at all. I think the babies would be eaten very quickly by any fish in the locality. Perhaps that is why they developed their cloning technique to start with. It is the only way they could possibly survive anywhere.

These crayfish are truly passive. The 3 adults aren't even eating any of the babies and they are all in a 40 gallon tank. The babies are about 3/8 inch long already too. Very strange crayfish!

Mine are so docile that sometimes I see smaller ones walk around on top of bigger ones without any sign of aggression ..... very easy to catch by hand they hardly even think of running....they are rascals...

I have seen the same behavior in my tank Terran. I can understand why it is believed these may have originated in a tank.

Vera, Terran,
What temperature and what photo period are you keeping them at to get them to breed?